Art of the transmission of sound



1927' K. M. LEDERER ART OF THE TRANSMISSION OF SOUND Filed March 20,1922 2 Slants-Shae;v 1

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WITNESS E5 1927' K. M. LEDERER V ART OF THE TRANSMISSION OF SOUNQShoots-Sheet 2 Fil'qd March 20. 1922 Jhvehtor Witne ss I Patented July5, 1927.

KARL mam LEDEBEE, F NEWARK, NEW JERSEY.

AM or rm: 'rnmsuissrou or scum Application fled latch 20, 1922. serialNo. 545,898.

My. invention relates to the mechanical and electromagnetical-mechanicaltransmission of sound by means of a diaphragm as it prevails inphonographs, telephone receivers,

microphones and transmitters for ordinary as well as wireless telephonyand the present invention has reference, more particularly, to a novelsound-transmisison device provided with a diaphragm which, due to itsspecial construction and the material of which it is made is ofextremelyIhi h elasticity and rigidity; and under ot erwise equalconditions, will transmit and reproducesounds more audibly than with theor- 16 dinary telephone diaphragm, since my novel diaphragm swings overa wider angle and therefore into motion a greater voiume of air. Theinvention is also adapted for use in producing original records forphono- 2 graphs, and the features above stated are also important inthis respect.

When used for so-ca led telephone receivers with electromagnetic action,the diaphragm is provided a with a cone shaped armature which shall swinbetween correspondingly shaped cores form pole pieces) therebypermitting the diaphragm to swing over a wider angle than that ofordinary receivers.

Theconstruction is also such that there is a special path provided forthe oscillating air, the conical armature acting as a valve or as pistonin a pump, driving the air into the ear or other channels adapted forthe reception, or transmission of the sound waves of such device as themegaphone and so called loud speakers and recording devices.

By the introduction of a stream of'air into the air chamber, formed bythe case and diaphragm of the receiver, which stream of air, whendesirable may be regulated in strength and which-stream of air must eventually pass throughthe only path left open for it, that is the openingin t e core around the cone of the diaphragm, the loudness of the soundshall be magnified stillfurther and possibly modulated.

This principle can readil be applied for phonographs and any simi ar 5devices, which depend u on a diap ragm asan agency, but with neit er ofthe above-mew tioned apparatuses or devices is the throttling action ofthe cone on the diaph an absolute necessity/and where desirab e the conemay be omitted and a flat armature be applied.

With the various objects and purposes herein-above stated, the presentinvention consists, primarily, in the-novel sound-transmitting devicehereinafter more fully set then finally embodied in the clauses of the vclaims, which are appended to, and which form an essential part of thesaid specification.

The invention is illustrated in the accompan ing drawings, in whichFigure 1 is a lan view of a diaphragm, showing one em odiment of theprinciples of the present invention; Figure 2 is a vertical section ofthe same; and Fi ure 3 is a vertical section of a-slightly mo ified.form of diaphragm.

Figure 4 is a transverse vertical section; Figure 5 a side elevation;and Figure 6 a plan view of a telephone receiver embracing the-novelfeatures of the present invention Figure 7 is a vertical sectionalrepresentation of another design. of receiver or transmitter; and Figure8 isa. side elevation of the same, with a portion of the device heingrepresented in section.

igures 9 and 10 are representations of other slightly modified forms ofreceivers; Figure 11 is a transverse vertical section of a double-actingloudvertical sectional 4 speaking receiver embodyin the principles ofthe present invention; an Figure 12 isa side elevation of the same.-

Similar'characters of reference are employed in all of the said abovedescribed views to indicate corresponding parts. Referring now moreparticularly to said Figures 1, 2 and 3, the numeral ,(1) represents thediaphragm disk, (2) thearmature, which, in all fi shape of a sing e ordouble cone, butwhich may also be only a plainpart of thediaphragm'or'which may in the'case of a nonma etic diaphragm consist ofa magnetic dis or a flat ring. 7

The armature (2) may be part of the diares where visible, has the phragmas in upper part of Figure (2) or in upper part at lefthand side of theView in Figure (3); or itmay be staked in, as in lower part (2) inFigure (2) or it may be cemented, riveted. or screwed to the diaphragmas indicated in right hand side section of Figure (3).

The diaphragm is provided with an arrangement of annular grooves andribs (3) which serve to increase flexibility and strength of thediaphragm. .The grooves and ribs (3) in Figure (2) are arrangedsymmetrically to the original plane of the diaphragm, while the groovesin Figure (3) are all on one side of the ori inal plane of thediaphragm. This latter -orm possesses certain advantages of manufacture.The

cross-section of such a diaphragm shall showor U shaped grooves orgrooves of a sinusoidal character.

Wherever the diaphragm disk is an integral part of the path of themagnetic flux it must be of a magnetic material. In cases, however,where it is acting solely mechanlcally, the principal requirements are,high flexibility, durability and permanency. Besides the already wellknown materials used for this purpose such as steel, iron, mica,phosphor bronze, aluminum, aluminum alloys, etc., I may use hardened andproperly tempered steel, cellon, celluloid and bakelite, condensite, andany other suitable compound or material capable of being moulded,pressed, machined or otherwise formed into the desired shape.

Referring now to Figure (4) the numerals (4), (4) indicate the twosections of pressed steel. or iron, connected to provide a suitable casewhich may serve either as a permanent magnet or as the yoke for anelectromagnet. The joint 5-5, between the two sections of the case ispreferably made in the form of annular bands folded over the twosections of the case for holding them together, the diaphragm (3) beingsuspended between the two sections of the case. The tubular core (6) ofthe electromagnet may either be solid or laminated (with laminationsarranged in a spiralic tube) as indicated in Figures 4 and 11, or it maybe drawn in the form of a tube as shown in Figures 9 and 10. p

This core is hollow so as to provide for an air path (7) and it iswidened out towards the center of the diaphragm for reception of thearmature 2.

The winding (8) of the electromagnet may either be wound on a lightspool or may be made selfsupporting as shown in Figures 9, 10 and 11.One end of each of the cores in Figure (4) is screw threaded and thelower coreis held in lace by means of a suitable nut (10). This nutservesalso as an ear funnel, by means of which the sound waves aredirected into the .ear. The u per core is screwed into an outlet (11) wich carries a tubular extension '(12) by means of which acousticconnection may be established to the other ear, thereby providing adouble acting phone. Numeral (9) indicates a washer which insulates thewinding from the case and (13), (13) are binding posts for theelectrical connection from the winding of the electromagnet to theexternal electrical circuit.

In the construction represented in F igures 7 and 8 the joint (5), (5)"between the two sections of the case is made either by a tight fit or byscrewing one section into the other. The lower case has arecess intowhich thediaphragm (3) is fitted. The upper section of case (4) hasthashape of a cone and is increased in'height at the ex pense of thelower sectionas there is only one winding (8) used in said lower sectionbeing formed with an inwardly extending and suitably curved portion, as17.

The tubular core (6) in Figure (7) has an extension (14) to which issecured by means of a collar (15) (which however could also be omitted)a horn or megaphone (16). The tubular core (6) as has been described inconnection with the deviceshown in Fig ure (4), but it may be added thatin Figure (6) the lower core is staked or screwed into the ear funnel(10). It is obvious that, when desirable, another megaphone, as 17,could be attached for the other side of the-diaphragm as indicated inFigures 11 and 12 of the drawings. If however only one megaphone is tobe used and both sides of the diaphragm shall be utilized and connectedto it, then acoustic connection has to be made so that said connectionsshall be in opposition, since there exists a phase difference of 180degrees between the two sides of the diaphragm.

In the upper section of Figures (7) and 8) a nozzle (18) is shownthrough which a continuous-stream of gas (air) is passed whereby thesound is amplified, the action and purposes of which has been reviouslystated. It is obvious that both sides of the receiver could be providedwith such gas (air) amplifiers, as indicated in said Figures 11 and 12of the drawings.

Referring now to the modification shown in Figure 7 of the drawings, thetwo sections 4, 4 are held together by the screws or rivets 5, wherebythe diaphragm is properly positioned and securely clamped in place.

This construction of the device differs from the device herein-beforedescribed, in that the core 6 is in the form of a tube, suitably widenedat the. bottom for reception of the armature 2 therein. In its up erend,

the core is staked or spun into t e, case,

where it also carries a nozzle 21 with which, by means of a flexibletube, acoustic connection (which is not shown) may be established to theother ear. The lower section of the case 4 is caved in at 22 to performthe functions of an ordinary receiver of a head set. A short pole piece11 also of a tubin is staked to the member 22 on the inner si e of thecase; but the latter could also assume this function if it were drawnand spun out as will be evident.

Figure differs from Figure 9 only in the lower part of the case and theform of diaphra m applied. Only one view has been given 0% themodifications represented by Figures 9 and-10, as it is thought, thatthe other views with the rest of the ordinary details could readily beimagined. Figure 10,

represents a receiver transmitter with a sinle cone-shaped armature andone may speak into the lower section of the case 20, which approachesthe form of a mouth piece of a transmitter and which is to be madepreferably of metal, but which could naturally be made of composition.One could also receive messages at the upper end, when acousticconnection to one or both ears is established by means of flexible orsemi-flexible tubes and earpieces. Itcan readily be imagined that such areceiver transmitter could be provided with bands, straps, etc.,

to be carried on the head by any telephone operator without being heldin any way by the hand, as such is already done when separate nstrumentsare provided for trans -mitter and receiver. Contrary to the ordinaryreceiver, the receiver and receiver transmitter just described cansuccessfully be operated over long and high resistance lines, as theirwindings consist of a great many turns over an iron core of substantialcross section-Wand an impedance (of several thousands of-"ohms-) whichcan readily be made congruent to the resistance, inductance andcapacitance of long lines.

The improved diaphragm, when same is combined with the air amplifier canreadily be used in the microphone of a phonograph, and similar devices,and the available motive power can be utilized to drive a small fan,

H turbine or bellows to furnish a continuous nected to the diaphragm ofthe receiver.

And a ain, reversing conditions, a hone, as just .cscribed, may be usedfor t e reproduction of phonograph records over long telephone lines orby means ofwireless telephony. Instead of using carbon microphones, orthe like, I- use one or a number of receiver transmitters and thenemploy the well known means of transmission f or ordinary or wirelesstelephone,

And, goin one step further, I establish a direct mec ianicaltransmission of the motions of a needle or lever, following with one endthe indentations of a (phonograph or gramophone, etc.) record, to thediaphragm of a receiver transmitter of the proper impedance andelectrodynamic capacity, so that b the motions of the diaphragm,electrica currents are generated in the phone congruent to the motionsof the diaphragm and the original soundways graphically imbedded in therecord..

It is evident, that by the latter procedure, less distortion of soundand electrical current waves will result; because one step of thetransformation is entirely eliminated, (the step from the diaphragm ofthe phonograph to the diaphragmof the microphone) and the process ofreproduction, especially with regards to clearness, has been materiallyimproved. In this respect (acoustically) the receiver is by far superiorto the microphone, and last but not least, the whole energy setfree bythe mechanically operated diaphragm of the phonograph receivertransmitter is available for the gen-. eration of electrical currentsand the em ciency must therefore reach a maximum.

From the foregoing description it will be evident, that I have produceda diaphragm, made of any suitable material, such as celluloid, cellon,and of analogous material, or of metal, for uses in devices for thetransmission of sound, and it is understood that such devices alsoinclude those for recording sound waves, devices for taking original'phonographic records, gramophones, and the like, and such other deviceswhich serve more strictly in the transmission ofsounds, as in telephonereceivers, transmitters, microphones, and the like.

I claim 1. A diaphragm for devices of the character specified comprisinga disk-sha ed element provided with a cone-shape armature, andconcentrically disposed annular grooves.

Q 2. A diaphragm for devices of the character specified comprising adisk-shaped element provided upon its opposite faces with cone-shapedarmatures, and concentrically disposed annular grooves.

3. A diaphragm for devices of the character specified comprising adisk-shaped cle ment provided with a cone-shaped armature of magneticmaterial, and concentrically disposed annular grooves.

4. A diaphragm for devices of the character specified comprising adisk-shaped element provided upon its opposite faces with cone-sha edarmatu res of magnetic material, an concentrically disposed annulargrooves.

5. In a device for the "transmission of sound, and similar apparatus, adiaphragm, associated with a tubular core, consisting of spirally wound=laminations, and a coil wound upon said core.

6. In a device for the transmission of sound, and similar apparatus, adiaphragm comprising a disk-shaped element provided with a cone-shapedarmature, associated with a tubular core provided with a coneshapedopening fitted-over said armature, and a coil wound upon said core.

\ 7.1n a device for the transmission of sound,'and similar apparatus, adiaphragm comprising a disk-shaped element provided with a cone-shapedarmature, associated with a tubular core consisting of spirally woundlaminations and provided with a cone-shaped opening fitted over saidarmature, and a coil wound upon said core.

8.121 a device for the transmission of sound, and similar apparatus, acasing comprising a pair of sections, a diaphragm disposed between andheld in place by said sections, means connected with said casing foradmitting air into the-same, associated with a tubular" core, and a coilsound upon said core.

9. In a device for the transmission of sound, and similar apparatus, acasing comprising a pair of sections, a diaphragm disposed between andheldin place by said sections, means connected with said casing foradmitting air into the same, a coneshaped armature associated with saiddiaphragm, a tubular core provided with a cone-shaped opening fittedover said armature, and a coil wound upon said core.

10. In a device for the transmission of sound, and similar apparatus, acasing comprising a pair of sections, a diaphragm disposed between andheld in place by said sections, and each section being provided with anair-inlet for admission of a continuous stream of air into said casingand about the diaphragm.

11. In a device for the transmission of sound, and similar apparatus, acasing comprising a pair of sections, a diaphragm disposed between andheld in place by said sections, and each section being provided with anair-inlet for admission of a continuous stream of air into said casingand about the diaphragm, associated with a tubular core, and a coilwound upon said core.

12. In a device for the transmission of sound, and similar apparatus, acasing comprising a pair of sections, a diaphragm disposed between andheld in place by said sections, and each section being provided with anair-inlet for admission of a continuous stream of air into said casingand about the diaphragm, a cone-shaped armature associated with saiddiaphragm, a tubular cone provided with a cone-shaped opening fittedover said armature, and a coil wound upon said core.

In testimony whereof, I have subscribed my name.

KARL MARTIN LEDERER.

